Mount Elgon’s highest peaks are formed by high points around a jagged rim enclosing one of the world's largest calderas, at 40km long and 8km wide. The tallest peak is the 4,321m Wagagi, followed by Sudek (4,303m), Koitobos (4,222m) and Mubiyi (4,210m). Mount Elgon is home to the World’s Largest Caldera. The Caldera was formed as a result of magma being drained from the chamber. When it could no longer support the overlying volcanic cone, it collapsed into a depression-like shape. Buffalos can be found on the lower slopes. The park is also home to a variety of small antelope and duiker, as well forest monkeys, including the black-and-white colobus and blue monkey. red-tailed monkeys have been reported after being thought to be locally extinct. Elgon is also home to at least 144 bird species.